Buenos Aires: The four Argentine sailors disappeared in late August -- when a storm off Brazil`s southern coast knocked out their luxury yacht`s mast and rudder -- but their families believe they`re still alive.

"You can survive adrift for a year or more," said Giovanna Benozzi, daughter of one and girlfriend of another of the four.

El Tunante II, a 12.5-meter vessel, "is made to float and remains adrift somewhere in the south Atlantic," she told AFP.

"We`re calling for all merchant vessels, fishermen and sailors around the world to add their eyes" to the search, Benozzi said.

"It`s been more than four months, but there are stories of people who have survived longer," Giovanni said.

Her optimism is based on the last communication from her father after the storm -- when he reported that, despite the damage, the hull was intact and the crew was all safe.

"We have not found any evidence to the contrary," in the months since, she said, insisting that when a boat sinks some evidence -- bottles, a life vest -- turns up.

But spotting a mast-less sailboat in the vast ocean is like finding the proverbial needle in a haystack. The lack of working communication devices compounds the difficulty -- and the drifting boat could be mistaken for simple debris.

Meanwhile, the clock is ticking.

"Food and water are no problem," Benozzi insisted. "We have strong hope."

Her father Jorge, a 62-year-old opthamologist, and her boyfriend Mauro Cappuccio, 35, are both experienced sailors. As are the other two on the boat, Alejandro Vernero, a 62-year-old cardiologist, and Horacio Morales, also 62.

The four had prepared for up to a year to embark on the planned journey from Buenos Aires to Rio de Janeiro.They left Buenos Aires on August 22, but four days later hit a storm off the coast of Brazil, with waves up to eight meters high.

A Norwegian merchant vessel spotted them early on August 27 but could not rescue them.

"They were transmitting their position to us for 10 hours, when the satellite phone ran out of batteries," recalled Benozzi. Since then, there has been no word.

The Brazil navy suspended its search in September, when a fishing boat found a half-submerged life raft off the coast of Rio Grande.

But Benozzi said she doesn`t believe the missing men were ever on that raft. She said she thinks they opened it and sent it out in the hopes it would help "give signals to aircraft and improve the chances of being caught on radar because of the metallic material."

"Satellite images prove that the boat is afloat and there are people moving around on board," Benozzi said.

She said tens of thousands of "people have voluntarily joined the search to scan satellite images on the Internet," facilitated by an international company.

Thanks to these efforts "we found a picture 90 percent compatible with the Tunante, according to expert analysis. But the bureaucracy and protocols of the Brazil navy meant they didn`t re-activate the search for 15 days.

"By then, the wind and tide had moved it miles," she said. The search was suspended again soon after.

The National Commission of Space Activities has made its satellite images available and the intelligence service of the Argentine military has offered its services to analyze them.

Family members are offering a sailboat as a reward for anyone who helps find the missing yacht and have opened a Facebook account and a web page where people can report any new information: www.buscandoaltunante.com.ar.

Castaways have been found before, Benozzi insisted. "We urge people to remain vigilant."